In a sample of Latino preschool dual language learners (DLLs) attending Head Start, the proposed study will examine executive functioning (EF) and bilingual development across the year as they relate to classroom practices and science readiness. The study will be the first to examine the bidirectional relationship between bilingualism and EF (i.e. bilingualism promoting EF development and EF promoting bilingual development), to highlight the mechanisms behind this relationship and inform opportunities for intervention for teachers. It will also determine if children's EF and bilingual ability across the year mutually predict science readiness. Lastly, this study will examine if level of support for the home language in Head Start classrooms influences EF and bilingual ability across the year. Results from this study will directly inform classroom practices that capitalize on DLL children's strengths to promote school readiness across domains. In the long-term, this study is a necessary step in a research agenda addressing the Latino achievement gap. Such efforts will help educators and policymakers utilize the unique strengths of DLL children within the American educational system, ultimately establishing a positive trajectory of academic success in preschool and beyond for our nation's future multilingual leaders.